<div class="modal-backdrop"/>
<div class="modal-body">
	<button>close</button>
</div>
<style>
.modal-backdrop{
	position:fixed;
	top:0;
	right:0;
	bottom:0;
	left:0;
	background-color:rgba(0,0,0,0.5);
	z-index:1;
}
.modal-body{
	position:fixed;
	top:3em;
	bottom:3em;
	right:20%;
	left:20%;
	padding:2em 3em;
	background-color:white;
	overflow:auto;
	z-index:2;
}
</style>